Air-oil pump



J y 1966 E. COLIN-SMiTH AIROIL PUMP 4 Sheets-Sheet 1 Original Filed Feb.27, 1961 Inventor ERIC COLIN-SMITH Attorney July 5, 1966 L a.COLIN*$MITH 3,259,068

v AIR-OIL PUMP Original Filea Feb. 27, 1961 4 Sheets-Sheet 2 ERICCOLIN-SMITH Attorney y 5, 1966 E. couwsmnm 3,259,068

AIR-OIL PUMP Original Filed Feb. 27, 1961 4 Sheets-Sheet 5 lnventor ERICCOLIN-SMITH AHorne y y 5, 1966 E. COLIN-SMITH 3,259,068

AIR-OIL PUMP Original Filed Feb. 27, 1961 4 Sheets-Sheet 4 ERICCOLIN-SMITH Attorney United States Patent Ofiice 3,Z59,%8 Patented July5, 1966 3,259,068 AER-01L PUMP Eric Colin-mith, Weiiesiey, Mass,assignor to Combustion Research Corporation, West Newton, Mass.Continuation of application Ser. No. 91,953, Feb. 27, 1961. Thisapplication Dec. 20, 1963, Ser. No. 333,790 2 Claims. (Cl. 1039) This isa continuation of application Serial No. 91,953, filed February 27,1961, now abandoned.

This invention relates to a combined air and oil pump deviceparticularly for use in oil burner installations wherein air and oil arerequired to be delivered at a regulated volume flow and pressure to anat-omizing nozzle for controlled combustion characteristics. It will beunderstood, however, that the device will have many other applications,for instance, in the agricultural spraying field.

The principal object of the invention is to provide a highly efiicientair-oil pump of simple and inexpensive construction which will enablethe air and oil volumes and pressures delivered by the pump to bequickly and easily adjusted to suit the requirements of the particularinstallation with which it is used.

A further important object is to provide such an air-oil pump which canbe utilized to replace existing oil pumps on the conventional gun typeburners to enable the ready conversion of such burners frominstallations relying solely on draft tube secondary air for combustionto relatively more efficient installations utilizing pressure primaryair for oil atomization according to the said co-pending application.

Still another important object is to enable the lair-oil pump to bedriven either directly or through a suitable coupling either from itsown motor or from the existing driving motor of the conventional oilburner installation, and more particularly to enable the air-oil pump tooperate efiiciently irrespective of the direction of rotation of thedriving motor so that the one pump unit will have universal applicationto make for very simple field installations.

The principal feature of the invention resides in providing a main bodyhousing separate rotary air and oil pumps driven from a common drive,and providing a flow controlling and metering valve unit associated witheach pump section whereby volume and pressure of flow delivered by eachpump is easily and quickly controlled without altering pump action.

Another and important feature reside in so constructing the pumps thatthey will function equally efficiently when rotated in either directionso that the inlet and outlet connections can be interchanged at willwhereby the device can be connected to drive motors irrespective oftheir direction of rotation.

In this connection, still another feature resides in forming the air-oilpump device with mounting means for convenient mounting in conjunctionwith conventional gun type burners to utilize the existing driving motorof such burners as the drive therefor.

Further, in thi connection, another important feature resides in formingthe flow controlling valving units as separate demountable andreversible units whereby connections to the pumps can be readilyachieved to accommodate reversal of pump rotation, thereby rendering theentire system completely universal so that it can be easily and quicklyinstalled in the field regardless of the direction of motor driveencountered, thus allowing standardization of the system, simplifyingproduction and reducing stocking of component parts.

Still another feature resides in providing the flow con trolling unitswith very precise and easily operated flow volume and pressure settingcontrols for adjustment of air and oil feed in the field.

Other features reside in the details of construction and arrangement ofthe air-oil pump device, and these and other features and objects willbecome apparent from the following detailed description taken inconjunction with the accompanying drawings in which:

FIGURE 1 is a perspective view partly broken away of an oil burnerinstallation employing an air-oil pump embodying my invention;

FIGURE 2 is an exploded perspective view of the airoil pump device shownin FIGURE 1;

FIGURE 3 is a longitudinal mid-vertical sectional view taken through thepumping section of the device;

FIGURES 4 and 5 are transverse, vertical, sectional views taken on thelines 44 and 5-5 of FIGURE 3;

FIGURE 6 is a horizontal, sectional view taken through the air flowcontrol unit; and

FIGURE 7 is a fragmentary, vertical, sectional view showing the oil feedthrough the bleed passage arrangement from the oil reservoir in the oilflow control unit up to the air pump rotor.

With reference to FIGURE 1, the air-oil pump, according to the presentinvention, is shown, generally designated at 1 being mounted inconjunction with a conventional type motor and blower unit 2 of agun-type domestic burner, the unit being carried on a suitable standard3 supported by a mounting base 4. The drive to the air-oil pump device 1is achieved from the motor of the motor and blower unit 2 as hereinaftermore fully described, and the device 1, including an air flow controlunit generally designated at 5 and an oil flow control unit generallydesignated at 6, is arranged to deliver air and oil at the requisitepressures and at the required volume flow through air and oil lines 7and 8 to feed a burner head 9, preferably of the type disclosed in myco-pending application, Serial No. 91,953, mounted in a draft tube 10projecting into a combustion chamber 11.

With reference to FIGURE 2, it will be seen that the air-oil pump device1 is separable from the air flow and oil fiow controlling units 5 and 6,and reference is to be had to FIGURES 3 to 5 for details of the airpumping section of the device generally designated at 12 and the oilpumping section of the device generally designated at 13.

The air pumping section 12 comprises a generally cylindrical casing 14.-having a cylindrical chamber 15 formed therein. Leading from the chamber15 through a downwardly projecting portion 16 of the casing 14 arespaced passageways 17 and 18. Eccentrically mounted within the chamber15 is a rotor 19 carrying radially slidable vanes 20, the rotor beingmounted on a shaft 21 supported in end bearing blocks 22 and 23 boltedor otherwise secured to the opposite end of the cylindrical casing 14.Mounted in suitable counterbores in the end blocks 22 and 23 aresuitable bearings 24 through which the shaft 21 extends. The shaftextends through an end seal 25 and a gland nut 26 beyond the end of theleft bearing block 22 for connection to a driving motor such as themotor of the motor blower unit 2 in FIGURE 1, the shaft end beingarranged for direct connection or for connection through any suitablecoupling as will be understood.

Secured to the outward end of the right hand bearing block 23 is an oilpump casing 27 having -a cylindrical chamber 28 formed therein.Communicating with the chamber 28 are passageways 29 and 30 havingenlarged internally threaded entrances 29 and 30'.

The shaft 21 has a reduced extension 31 which projects through asuitable end seal 32 into the chamber 28 with the axis of the reducedextension 31 being eccentric to the axis of the chamber.

Mounted on the reduced shaft extension 31 is an oil pumping rotor 33secured to the shaft by means of a a key 34, the rotor carrying a seriesof radially slidable vanes 35.

The outer face of the oil pump casing 27 is closed by a block 36 havinga reduced portion extending into the chamber 28 and a cap 37, suitablegaskets 38 and 39 being provided to effect a complete seal, and furthergasket 40 being provided between the casing 27 and the right hand endbearing block 23.

Secured to the downwardly projecting portion 16 of the air pump casing14 is a mounting face or base plate 41 having formed therein registeringports 17' and 18 adapted to register with the, passageways 17 and 18. Asuitable gasket 42 is interposed between the plate 41 and the casingbase 16.

Leading up through the base plate 41 centrally thereof and up throughthe downward extending portion 16 of the air pump section casing 14 is apassageway 43 which terminates in a small orifice 44 opening into theair pumping chamber 15. Leading laterally from the passage way 43 arefeed passages 45 which are arranged to intersect with passages 46 in theend bearing blocks 22 and 23, these passages containing wicks 47 leadingto the bearings 24 whereby oil delivered under pressure as hereinaftermore fully explained through the passage 43 will feed into the airchamber 15 to provide an oil seal between the passages 17 and 18 andwill feed laterally to the wicks 47 to be delivered to the bearings 24for lubrication.

With the pumps illustrated, it will be understood that a pumping actionwill be achieved regardless of which direction of rotation is impartedto the pumping rotors 19 and 33. With the direction of rotationcounterclockwise, as shown in FIGURE 4, the vanes 20 of the air pumpwill suck air in through the passageways 18 which thus form the intakepassages and will discharge compressed air through the passages 17 whichthus form the discharge passages. It will be understood, of course, thatthe reverse rotation of the rotor will reverse the function of thepassages 17 and 18 as intake and discharge passages.

Viewing FIGURE 5, it will be apparent that with the counterclockwiserotation oil will be sucked into the pumping chamber 28 through thepassageway 30 which will then form the intake passage and will bedelivered out through the passage 29 which will then form the dischargepassage. Upon reversal of rotor rotation, of course, the function of thepassages will be reverse-d. The manner in which the air and oil fiow iscontrolled is an important aspect of the invention, and with referenceparticularly to FIGURES 2 and 6, it will be seen that the dischargeport-s 17 and 18' formed in the base plate 41 are symmetrical withrespect to each other and with respect to the base plate and with thecentral passage 43. This relationship of the ports is important withrespect to the simplification of the ease with which pump can bereversed through the simple rotation of the air flow control unit orblock from end to end; that is, rotation through 180 in its own plane ashereinafter more fully explained. Assuming that the direction ofrotation is such that the ports 18 form the intake ports and the ports17 form the discharge ports from the air pumping section, the air flowcontrol unit 5 is arranged as illus trated in FIGURE 2 and FIGURE 6. Inthis connection it will be seen that this unit comprises a block havingan intake passage 48 leading in from one end to a cross passage 49plugged at opposite ends with the cross passage opening through ports 50which are adapted to register with the ports 18 in the mounting basewhen these latter ports are forming the intake ports for the air pumpsection.

Preferably an air silencer generally designated at 51, as particularlyseen in FIGURE 6, is threaded into the entrance to the intake passage 48to provide for low level sound of operation of the air pump, the devicecomprising a cylinder housing a series of baflles 52 and 53 providingfor a tortuous air flow path.

The air flow control block 5 is provided with a further cross passage 54parallel the passage 49 again plugged at the ends, and this passagecommunicates through ports 55 in the upperface of the blockcorresponding to the ports 50. These ports are adapted to register withthe ports 17' in the base plate 41 when the latter ports form dischargeports for the air pumping section.

Thus it will be seen that the ports 50 and 55 are symmetrical withrespect to each other and with respect to the air control unit or block5 and also with respect to a central orifice 56 through the block 5 sothat should the direction of the air pump rotation be reversed, a simpleend-to-end shifting of the block 5 will maintain the intake ports 50 inregistering communication with the intake ports of the air pump sectionnow the ports 17 and vice versa. Leading from the cross passage 54, is athreaded bore 57 opening into an enlarged bore 58 opening through theend of the block. Mounted in the bores 57 and 58 is a valve devicegenerally designated at 59 which has a reduced hollow inner end 60threaded into the threaded bore 57 and.

an enlarged internally threaded sleeve portion 61 having discharge ports62 communicating to a peripheral groove 63 in the perimeter thereof. Thevalve is provided with a shoulder 64 and suitable O-rings 65, oneencircling the threaded portion 69 and the other the sleeve portion 61be neath the shoulder 64, provide for fluid seals. Threadably mounted inthe sleeve portion 61 is a spindle 66 carrying a needle or pinprojection 67 extending into the reduced sleeve portion 61. Outwardly ofthe needle portion 67, the spindle is provided with a bevelled shoulder68 arranged to seat on a bevelled valve seat 69 to block fluid flowthrough the bore 57. The needle 67 is provided with a V-groove formation70 therein which permits an increasing volume flow as the spindle 66,isbacked off to raise the shoulder 68 from the valve seat 69. It hasbeen found that this V-groove gives a very precise volume flow controlunder spindle movement. The spindle 66 projects through a cap or gland71 and is provided with a suitable control wheel 72. Leading laterallyfrom the bore 58 is a discharge port 73 which receives an air flow pipewhich constitutes the air line 7 for delivering air to the burner heador other installation.

In addition to the flow path through the valve-controlled passageleading to the discharge port 73 is a further flow path leading to anair exhaust port 74 communicating with the atmosphere through an airsilencer 51. This latter flow path is aiforded through the provision ofa bore 75 parallel to the bore 58 and terminating in a reduced threadedbore 76 opening into the cross passage 54. A pressure control valvegenerally designated at 77 is mounted in the bores 75 and 76, the valvecomprising a hollow body 78 having a reduced threaded portion 79threading into the bore'76 with the body opening into the cross passage54. The body is provided with a shoulder 80 and suitable O-rings orgaskets 81 are used to effect seals against air leakage exteriorally ofthe body.- Formed within the body 78 is a valve seat 82 with whichco-operates a ball valve 83 held by a cup 84 carried on a stem 85slidably received and guidably supported in a threaded sleeve 86 whichthreadably engages an internal threading 87 of the body, the sleeve 86being provided with a slot 86 in its end for screw driver engagement. Acap 88 encloses the sleeve 86 in the body 78.

Sleeved on the stem 85 is a spring 89 which is received in a counterbore90 in the sleeve 86 and this spring acts on the cup 84 to urge the ballto seat against its valve seat 82. By adjusting the sleeve 86 axially ofthe body 78, the spring tension and hence pressure at which the ballwill lift from its valve seat to allow air flow therepast can beprecisely and accurately set.

The body 78 has ports 91 therein communicating with an external groove92 to allow air passing ball valve 83 to escape to the air exhaust port.

Thus, by setting the valves 59 and 77, the requisit air flow through theair line 7 can be accurately predetermined as to volume and pressure,and if the direction of the air pump rotation is reversed to reverse thedirection of air flow, the block 5 can be quickly and easily reversed byturning end to end to accommodate such pump reversal.

FIGURE 2 shows the details of the oil flow control unit and assuming oilis entering the oil pump section 13 through the infeed line 93, then oilwill be discharged from this section through the discharge oil line 94.The line 94 leading from the oil pump unit connects through an intakeport 95 provided in the oil flow control unit 6, which is in the form ofa block of corresponding size to the block 5, and this intake port 95communicates with a central oil well 96 from which leads a passageway97, flow control through which is controlled by a valve 59',corresponding ponding to the valve 59 described in connection with theair flow control unit, and discharging from the valve-controlledpassageway 95 is a discharge port 98 connected through an oil linecomprised by the oil line 8 referred to in FIGURE 1.

Also in communication with the well 96 is a passageway 99 controlled bya pressure control valve 77 corresponding to the pressure control valve77, and leading from this valve-controlled passageway 99 is a by-pass100 communicating through oil line 101 to the intake side of the oilpump section.

Projecting up through the oil well 96 is a body member 103, FIGURE 7,threaded into a boss 104 at the bottom of the block 6. A cylinder 105having a reduced lower end received in the body member 103 and a reducedthreaded upper end threaded into a counterbore formed in the undersideof the block 5 is provided internally with a needle valve seat 106 andfeed passages 107 and a fine bore 108 leading through the upper end tocommunicate with the central passages 56 and 43 formed through the aircontrol block and the air pump casing respectively. A needle valve 109having a threaded stem 110 is mounted in the body member 103 and isoperated by means of a control wheel 111, the needle valve being movedto and from the needle valve seat 106 to regulate flow through the finebore 108 into the registering central passages 56 and 43 providing foroil flow to the interior of the air pump chamber and oil wicks 47. A cap112 encloses the control wheel 111 and suitable sealing gaskets 113 areprovided to afford a seal between the body member 103 and the boss 104and between the cap 112 and body member.

The air-oil pump, according to the invention, may conveniently bemounted on any standard mounting bracket used in conventional gun-typeoil burner installations when it is to be used with such installations,and the intake side of the oil pumping section 13 can be coupled to theoil line 114 leading from a tank or other oil supply, such connectionbeing conveniently effected through a fitting 115 which provides for thereturn of excess oil through the line 101, as shown in FIGURE 1. The airand oil control units 5 and 6 will, of course, be secured to themounting face 41 of the air-oil pump unit to suit the direction ofrotation which will be imparted to the pumping devices. The output fromthe air flow control unit 5 will be connected to the air line 7 as willthe output of the oil flow control unit 6 be connected to the oil line8. Then through the valves 59 and 59 and 77 and 77', the air and oilvolume and pressure can be quickly and-easily set to suit the particularrequirements of the installation. It will be noted that for conveniencein manufacture and use, all pressure regulating and volume controlValves are interchangeable in their mountings.

While I have disclosed the preferred embodiments of my invention, itwill be understood that variations in the details of construction and inthe component parts employed may obviously be made by those skilled inthe art without departing from the spirit of the invention or scope ofthe appended claims.

What I claim is:

1. A reversible air and oil pump device adapted to be driven in a firstdirection or a reverse direction comprising: a fixed housing defining,an air pump chamber, and an oil pump chamber; a reversible rotary airpump device rotatably mounted in said air pump chamber, a reversiblerotary oil pump device rotatably mounted in said oil pump chamber; acommon drive means for said air and oil pump devices; said housingincluding, a mounting face, and further characterized in defining, aplurality of individual pass-age means constituting inlet and outletpassages to said oil pump chamber, and a plurality of individual passagemeans constituting inlet and outlet passages to said air pump chamber,said passages to said air pump chamber terminating in openings on saidmounting face, said openings being substantially symmetrical andregularly disposed about an axis; a flow-control unit associated witheach of said pump outlets to receive the fluid delivered thereby, saidunits each including; an outlet passage formation communicable withtheir respective pump outlets and with an external installation,adjustable valve means for controlling volume flow through said outletpassage, an air by-pass communicating said air outlet passage with theatmosphere and adjustable pressure delivery valve means controlling airflow therethrough, an oil by-pass communicating said oil outlet passagewith an intake side of said oil pump and adjustable pressure deliverymeans controlling oil flow therethrough, said air flow control unitincluding an air intake passage formation, said air intake and airoutlet passage formations having openings communicable with therespective openings of said housing, said air flow control unit furtherincluding a mounting face, said air intake and outlet passage formationseach having at least one opening cooperable with the respective inletand outlet openings of said housing mounting face, said oil flow controlunit comprising; an oil control block adapted to be mounted in face toface relationship with a face of said air control unit opposite to saidmounting face; said oil control block having a well therein communicablewith said oil outlet passage formation; and bleed passage meanscommunicating said oil block well through said air block and saidhousing mounting face with said air pump chamber, said bleed passageterminating in a bore of reduced diameter intermediate said inlet andoutlet passage means to provide therebetween in cooperation with saidair pump an oil seal, and means controlling oil feed through said bleedpassage means.

2. A reversible air and oil pump device adapted to be driven in a firstdirection or a reverse direction comprising: a fixed housing defining,an air pump chamber, and an oil pump chamber, a reversible rotary airpump device rotatably mounted in said air pump chamber, a reversiblerotary oil pump device rotatably mounted in said oil pump chamber; acommon drive means for said air and oil pump devices; said housingincluding, a mounting face, and further characterized in defining, aplurality of individual passage means constituting inlet and outletpassages to said oil pump chamber, and a plurality of individualpass-age means constituting inlet and outlet passages to said air pumpchamber, said passages to said air pump chamber terminating in openingson said mounting face, said openings being substantially symmetrical andregularly disposed about an axis; a flow-control unit associated witheach of said pump outlets to receive the fluid delivered thereby, saidunits each including; an outlet passage formation communicable withtheir respective pump outlets and with an external installation,adjustable valve means for controlling volume flow through said outletpassage, an air by-pass communicating said air outlet passage with theatmosphere and adjustable pressure delivery valve means controlling airflow therethrough, an oil by-pass communicating said oil outlet passagewith an intake side of said oil pump and adjustable pressure deliverymeans controlling oil flow therethrough, said air flow control unitincluding an air intake passage formation, said air intake and airoutlet passage formations having openings communicable with therespective openings of said housing, said air flow control unit furtherincluding a mounting face, said air intake and outlet passage formationseachhaving at least one opening cooperable with the respective inlet andoutlet openings of said housing mounting face, said oil flow controlunit comprising; an oil control block adapted to be mounted in face toface relationship with a face of said air control unit opposite to saidmounting face; said oil control block having a well therein communicableWith said oil outlet passage formation; and bleed passage meanscommunicating said oil block well through said air block and saidhousing mounting face with said air pump chamber, said bleed passageterminating in a bore of reduced diameter intermediate said inlet andoutlet passage means to provide therebetween in cooperation with saidair pump an oil seal, means controlling oil feed through said bleedpassage means; said air pump housing being provided with passage meansrunning laterally of said bleed passage means, and means incommunication with said latter passage means for feeding oil to said airand oil pump driving means to seal said air chamber at opposite sides ofsaid rotary air pump.

References Cited by the Examiner UNITED STATES PATENTS 849,482 4/1907Machlet 23022 2,107,152 2/1938 Huber. 2,409,477 10/1946 DeLancey 103-62,477,371 7/1949 Hartzler 1033 2,575,074 11/1951 Senninger 103-62,655,108 10/1953 Osborne 1033 2,667,125 l/1954- Foss et al. 103422,794,398 6/1957 Munroe 103--3 MARK NEWMAN, Primary Examiner.

DONLEY .T. STOCKING, Examiner.

W. L. FREEH, Assistant Examiner.

1. A REVERSIBLE AIR AND OIL PUMP DEVICE ADAPTED TO BE DRIVEN IN A FIRSTDIRECTION OR A REVERSE DIRECTION COMPRISING: A FIXED HOUSING DEFINING,AN AIR PUMP CHAMBER, AND AN OIL PUMP CHAMBER; A REVERSIBLE ROTARY AIRPUMP DEVICE ROTATABLY MOUNTED IN SAID AIR PUMP CHAMBER, A REVERSIBLEROTARY OIL PUMP DEVICE ROTATABLY MOUNTED IN SAID OIL PUMP CHAMBER; ACOMMON DRIVE MEANS FOR SAID AIR AND OIL PUMP DEVICES; SAID HOUSINGINCLUDING, A MOUNTING FACE, AND FURTHER CHARACTERIZED IN DEFINING, APLURALITY OF INDIVIDUAL PASSAGE MEANS CONSTITUTING INLET AND OUTLETPASSAGES TO SAID OIL PUMP CHAMBER, AND A PLURALITY OF INDIVIDUAL PASSAGEMEANS CONSTITUTING INLET AND OUTLET PASSAGES OF SAID AIR PUMP CHAMBER,SAID PASSAGES TO SAID AIR PUMP CHAMBER TERMINATING IN OPENINGS ON SAIDMOUNTING FACES, SAID OPENINGS BEING SUBSTANTIALLY SYMMETRICAL ANDREGULARLY DISPOSED ABOUT AN AXIS; A FLOW-CONTROL UNIT ASSOCIATED WITHEACH OF SAID PUMP OUTLEST TO RECEIVE THE FLUID DELIVERED THEREBY, SAIDUNITSEACH INCLUDING; AN OUTLET PASSAGE FORMATION COMMUNICABLE WITH THEIRRESPECTIVE PUMP OUTLETS AND WITH AN EXTERNAL INSTALLATION, ADJUSTABLEVALVE MEANS FOR CONTROLLING VOLUME FLOW THROUGH SAID OUTLET PASSAGE, ANAIR BY-PASS COMMUNICATING SAID AIR OUTLET PASSAGE WITH THE ATMOSPHEREAND ADJUSTABLE PRESSURE DELIVERY VALVE MEANS CONTROLLING AIR FLOWTHERETHROUGH, AN OIL BY-PASS COMMUNICATING SAID OIL OUTLET PASSAGE WITHAN INTAKE SIDE OF SAID OIL PUMP AND ADJUSTABLE PRESSURE DELIVERY MEANSCONTROLLING OIL FLOW THERETHROUGH, SAID AIR FLOW CONTROL UNIT INCLUDINGAN AIR INTAKE PASSAGE INFORMATION, SAID AIR INTAKE AND AIR OUTLETPASSAGE FORMATIONS HAVING OPENINGS COMMUNICABLE WITH THE RESPECTIVEOPENINGS OF SAID HOUSING, SAID AIR FLOW CONTROL UNIT FURTHER INCLUDING AMOUNTING FACE, SAID AIR INTAKE AND OUTLET PASSAGE FORMATIONS EACH HAVINGAT LEAST ONE OPENING COOPERABLE WITH THE RESPECTIVER INLET AND OUTLETOPENINGS OF SAID HOUSING MOUNTING FACE, SAID OIL FLOW CONTROL UNITCOMPRISING; AN OIL CONTROL BLOCK ADAPTED TO BE MOUNTED IN FACE TO FACERELATIONSHIP WITH A FACE OF SAID AIR CONTROL UNIT OPPOSITE TO SAIDMOUNTING FACE; SAID OIL CONTROL BLOCK HAVING A WELL THEREIN COMMUNICABLEWITH SAID OIL OUTLET PASSAGE FORMATION; AND BLEED PASSAGE MEANSCOMMUNICATING SAID OIL BLOCK WELL THROUGH SAID AIR BLOCK AND SAIDHOUSING MOUNTING FACE WITH SAID AIR PUMP CHAMBER, SAID BLEED PASSAGETERMINATING IN A BORE OF REDUCED DIAMETER INTERMEDIATE SAID INLET ANDOUTLET PASSAGE MEANS TO PROVIDE THEREBETWEEN IN COOPERATION WITH SAIDAIR PUMP AN OIL SEAL, AND MEANS CONTROLLING OIL FEED THROUGH SAID BLEEDPASSAGE MEANS.